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Robert, RV Mechanic
Category: RV
Satisfied Customers: 12813
Experience:  18 yrs. RV experience including Cummins North West, Country Coach, Monaco Coach - vendor certified.
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I have a 400 hp cummins motor on my american coach..rv.

Customer Question

I have a 400 hp cummins motor on my american coach rv. what performance parts do you recommend where I can reach upwards of 500+ hp?
Submitted: 8 years ago.
Category: RV
Expert:  Robert replied 8 years ago.

Hi There!!!


Thanks for Choosing Just Answer...


Do you have a rear radiator or side mounted radiator?


Thanks. Robert

Customer: replied 8 years ago.
Side mounted radiator.
Customer: replied 8 years ago.
just some more info. the engine is a cummins ISL 8.9 Liter. I found something online called Dr. Performance predator performance module. Any opionons on this module?
Expert:  Robert replied 8 years ago.



Here are my feelings on any upgrades. First off this is a brand new unit. You need to be very careful on anything you do to alter the horsepower. The reason being is you can void the warranty on your engine and any repairs would not be covered. Another issue I see is this is a 2009 and I would not want to experiment with after market products with the new emissions. I do know in some cases Cummins can upgrade the computer software to a higher Horse power. They do charge a hefty fee for doing this. What I would do at this point is get your 8 digit engine serial number and call Cummins directly to see if you can in fact increase the horsepower with a simple calibration. When you increase horse power other things components need to be factored in such as the turbo and the transmission converter. I would hate to see anything happen to this new unit. I asked about the radiator because on some of the rear radiators a two speed fan controller can be added that is approved by cummins, this can not be done on the side mounted radiator. Hope this helps, if you have any other concerns or comments please feel free to contact me.


Customer: replied 8 years ago.

Thanks Robert...


I will call Cummins tomorrow and see if they offer any calibrations to this motor. So just to confirm, you don't think the module is a good idea because of the emmisons issue?

I still can't understand why american coach would put a 400hp motor in a coach that weighs around 40,000 lbs. It has a hard time climbing hills with my tow vehicle attached.

Expert:  Robert replied 8 years ago.

I do not... I have seen items like banks systems installed and it creates a issue with cummins.. That is allot of weight for a ISL. You may be able to get 25 more horse power with a calibration. Cummins would charge a hefty fee because it prevents others from buying a smaller engine and upgrading.. Anything you do I would get it approved with cummins.. In 2008 new emission standards came out and I would really be concerned about how any after market product reacts or if any testing has been done. Hope this makes sense.


Customer: replied 8 years ago.
Yes, it makes sense. what does ISL stand for?
Expert:  Robert replied 8 years ago.

Here are the engine meanings.. so IS is Interact System and L is 9 liter engine models


Engine Series

IS = Interact System (i.e. ISX, ISB)
Q/QS = Signifies that an industrial engine is electronically controlled. QS stands for QUANTUM SYSTEM CONTROLS
B = B series engine line, includes 3.3 , 3.9, 4.5 and 5.9 liter engines. Offered in both fully mechanical and electronic models. 5.9 liter engine is available in both industrial and automotive versions.
C = C series engine line, includes only 8.3 liter engines. Offered in both fully mechanical and electronic models, industrial and automotive versions available.
E = On older engine models this meant the engine was electronic. EXAMPLE: K2000E
K = K series engine line, includes 19, 23, 38, 45, 50 and 60 liter engine models.
L = L series engine line, includes older 10 liter and current 9 liter engine models. Industrial and automotive versions available.
M = M series engine line, includes M11, 11liter engines only. Industrial and automotive versions available.
N = N series engine line, no longer being produced for U.S. market. Included NTA855 and N14 engine series. Industrial and automotive versions available.
T = T series engine line such as the QST30.
X = X series engine line, includes 15 liter engines only. Industrial and automotive versions available.


Thank You!! Please hit ACCEPT for my efforts, Positive feedback and BONUS welcomed!!!!

Robert and 3 other RV Specialists are ready to help you
Customer: replied 8 years ago.
Thanks for all your help Robert. Again I will contact Cummins tomorrow and hopefully they can help me further with some hp gains. Take Care